Xerographic transfer apparatus



y 1967 T. c. MURRAY ET AL 3,319,604

XEROGRAPHIC TRANSFER APPARATUS Filed March 2, 1964 2 Sheets-Sheet l INVENTORS. THOMAS C. MURRAY FRANKLIN S. REESE FRANK A ROSEL Ll ROBERT- A. SCHAEFFER OSEPH B. STONE Bfn n M ATTORNEYS y 1967 T. c. MURRAY ET AL 3,319,604

XEROGRAPHIC TRANSFER APPARATUS Filed March 2, 1964 2 Sheets-Sheet 2 ATTORNEYS V m m ww\ l a m M on \lG 8 8. N u E Wm mo EREEAN m I V U H g 3 NM c r W 1 535 g k m A E i Q a; mmmmm M E a a mmw M 0 v TFFRO Y a B United States Patent Ofifice 3,319,604 XEROGRAPEHC TRANSFER APPARATUS Thomas C. Murray, Rochester, Franklin S. Reese, Victor,

Frank A. Roselli, Webster, Robert A. Schaefier, Rochester, and Joseph B. Stone, Penfield, N.Y., assignors to Xerox Corporation, Rochester, N .Y., a corporation of New York Filed Mar. 2, 1964, Ser. No. 348,340 7 Claims. (Cl. 118-637) This invention relates to an electrostatic image transfer device and particularly to an improved transfer device for aligning a sheet of support material on the surface of a xerographic plate and electrostatically transferring part of the image to the support material.

In the process of Xerography as described, for example, in Patent No. 2,297,691 issued to Chester F. Carlson, a Xerographic plate comprising a layer of photoconductive insulating material on a conductive base is given an electrostatic charge, exposed to a light image to create an electrostatic lightened image on its surface, and then dusted with an electroscopic powder to produce a powder image. The apparatus of the present invention is useful in transferring such powder images to sheets of paper, paper offset masters, and metal masters.

The primary object of this invention is to improve xerographic transfer devices so that a sheet of support material may be properly aligned on a Xerographic plate simultaneously with the transfer of a powder image from the plate surface to the sheet of support material.

It is also an object of this invention to improve xerographic transfer apparatus so that an electrostatic transfer device may be drawn across the surface of a Xerographic plate and a sheet of support material deposited on the plate surface to receive a powder image therefrom.

It is also an object of this invention to improve Xerographic transfer apparatus to facilitate the transfer of powder images to a metal master by precharging the xerographic plate as the metal master is superimposed on the plate surface.

It is also an object of this invention to improve xerographic transfer apparatus so that it is not necessary to position a sheet of support material on a xerographic plate prior to the transfer operation, thus minimizing the possibility of smearing the powder image, and to improve the apparatus so that it can be simply and economically constructed and easily operated.

These and other objects of this invention are obtained by means of an electrostatic transfer device containing electrostatic charging members, a set of support material feed rollers and support material alignment means operatively connected to feed a sheet of support material onto the surface of a xerographic plate and to transfer a powder image from the plate to the support material.

For a better understanding of the invention as well as other obiects and further features thereof, reference is had to the following detailed description of the invention to be read in connection with the accompanying drawings, wherein:

FIG. 1 is a left-side perspective view of a xerographic transfer apparatus embodying the present invention with portions broken away for purposes of clarity;

FIG. 2 is a front view of the apparatus shown in FIG. 1 with portions broken away to show internal structures,

FIG. 3 is a left-side view taken along lines 33 of FIG. 2;

FIG. 4 is an enlarged detailed view of a shaft retainer taken along lines 4-4 of FIG. 2.

The device shown in FIG. 1 consists of a front frame plate 19 and a rear frame plate 12 which support a pair of plate guides 14, a pair of corotron tracks 16, a corotron 3,319,604 Patented May 16, 1967 guide channel 18 and a corotron guide shaft 20. A Xerographic plate 22 is positioned between the frame numbers 10 and 12 on the plate guides 14 and has a photoconductive surface 24 on the top surface thereof. Prior to use of this apparatus, the xerographic plate has been charged, exposed, and developed in a xerographic camera of the type disclosed in co-pending application Serial No. 348,950 filed March 3, 1964, in the names of Norbett H. Kaupp, Thomas C. Murray, and Russell R. Roberts, and has thereon a powder image of an original copy that is to be reproduced. An electrostatic transfer device 26 is supported above the Xerographic plate by means of a roller 28 mounted in the guide channel 18 and a pair of bearing blocks 30 mounted on the guide shaft 20. The electrostatic transfer device 26 spans the width of the xerographic plate 22 and is moveable along the guide rail 29 and the guide channel 18 over the length of the Xerographic plate. The guide blocks 30 are formed integrally with a left-side frame 32 and the roller 28 is mounted for rotation on a shaft 34 which is journaled in a right-side frame 36.

A sheet of support material 38 adapted to receive a powder image of the copy being reproduced is supported from an inclined plate 40 and fed through the electrostatic transfer device by means of a pair of resilient drive rollers 42. The drive rollers 42 are mounted on a shaft 44 which are journaled in the side frames 32 and 36 by means of bushings 46 and contain a pinion 48 on each end which mesh with the corotron tracks 16, shown herein as a pair of gear toothed racks. As the electrostatic transfer device 26 is moved along the length of the Xerographic plate 22, the pinions 48 mesh with the teeth of the track 16 and rotate the shaft 44 and the resilient drive rollers 42. The linear movement of the drive rollers 42 is approximately the same as the linear movement of the electrostatic transfer device 26 across the surface of the Xerographic plate. As the support material 38 is fed onto the surface of the plate it is efiectively tacked to the plate by the electrostatic charge, thus preventing any relative movement between the plate and the support material.

Inside the cover housing 51 of the transfer device there is an L-shaped support member 52 secured between the side frames 32 and 36 by means of bolts and nuts 53. A corotron or electrostatic charging device 54 is suspended from the support member 52 by means of bracket 56, lug 58 and nut 60. The lug 58 and the nut 60 are adjustable to vary the height of the corotron 54 from the surface of the xerographic plate. A compression spring 62 is mounted around the lug 58 between the corotron 54 and the bracket 56 to hold the corotron in position. The corotron 54 consists of a shield 64 around at least one wire 66 which gives off a corona discharge when a lr'gh potential is applied thereto. The corona discharge is effective to place an electrostatic charge on. the surface of the sheet of support material 38 as the corotron is moved over the surface of the Xerographic plate. The electrostatic discharge from the corotron effectively tacks the sheet of support material 38 to the plate surface and prevents relative movement between the support material and the Xerographic plate. The electro static charge on the surface of the sheet of support material 38 attracts the powder image on the plate surface and causes it to adhere to the surface of the support material so that a powder copy of the image to be reproduced remains on the surface of the support material when the support material is removed from the surface of the Xerographic plate. 7

A second corotron 68 is suspended from a support number 70 by means of a bracket 72, a lug 74, a nut 76 and a compression spring 78 in the same manner as the corotron 54. The corotron 68 also consists of a shield 80 and at least one corona wire 82 which, when connected a 4-- to a high potential source gives off a corona discharge thereto over a pair of nylon bearing surfaces 108 mounted which is effective to place an electrostatic charge on the in the support member 50. The other ends of the chains xerographic plate surface. This corotron 68 is used to 107 are secured to a lifting arm 110. The lifting arm 110 transfer powder images from the xerographic plate to has a U-shaped bottom which encompasses the shaft 44 metal masters in a manner similar to that described in 5 and, when moved upward, lifts the shaft 44 vertically in Patent No. 3,004,860. As pointed out in the above cited the slots 86. Vertical movement of the shaft 44 lifts the patent, when transferring powder images to a metal surdrive rollers 42 away from the inclined plate 40 and lifts face, the electrostatic transfer charge is placed on the the deflectors 94 upward permitting the registration guide surface of the xerographic plate, rather than on the sur- 86 to extend above the surface of the inclined plate 40. face of the support material. This electrostatic charge A sheet of support material may then be placed on an effectively holds the metal master to the surface of the inclined plate and properly registered against the registraxerographic plate and the charge effectively transfers the tion guide 86. When the button 102 is released the action powder from the xerographic plate to the surface of the of the leaf spring 98 forces the shaft 44 downward so that metal master. As can be seen in FIG. 3, when the electhe drive rolls 42 are on top of, and in contact with, the trostatic transfer device is moved from left to right a sheet of support material, and the sheet registration guide metal master would be moved beneath the drive rollers 86 is deflected downward beneath the surface of the in- 42 onto the surface of the xerographic plate and if the clined plate 40.

corotron 68 is energized the electrostatic discharge would At this point the operator may depress the switch occur between the xerographie plate and the metal master. button 84 actuating switch SW-l to energize the partic- A plate 69 shields the surface of the Xerog'raphic plate ular corotron that he has previously selected for use with from extraneous light keeping the area between the supthis type of support material, and draw the electrostatic port material and the corotron 68 in the dark during the transfer device 26 forward across the surface of the xerotransfer process. This apparatus provides substantial imgraphic plate. Power will be supplied to corotrons by provement over that disclosed in the above cited patent means of wires 85 which extend below the surface of the in that it eliminates the need for a dark slide and the ac- 5 plate guides 14 to form a large flexible loop which percompanying operations of inserting and removing the dark mits movement of the transfer device along the tracks 16.

slide during transfer. The wires 85 are connected to any suitable high poten- An electrical switch button 84 extends through the tial power supply. The sheet of support material 38 will outer cover of the transfer device to actuate a switch SW-l he moved downward y the ta f th drive r llers which connects the corotrons 54 and 68 to a suitable 30 42 onto the surface of the xerogr-aphic plate and be elecsource of electrical power, not shown, to energize the trostatically tacked thereto by the electrostatic discharge wires 66 and 82. A separate selector switch, which is from the corotron 54 or 68. After the electrostatic transalso not shown in the drawings, is used to determine fer 26 has complet ly tra s the g phic plate and which corontron 54 or 68 is to receive power fr the the sheet of support material 38 has been fed through the ower supply, The operator deter i e h th th electrostatic transfer device then the operator may release powder image is to be transferred to a paper or metal the switch 84 cutting off power to the corotrons and move sheet of support material and accordingly switches the the electrostatic transfer device hack t0 its Original P power supply to the corotron 54 or 68 respectively, then tiOn- The pp material 38 m y w be r moved from upon actuation of switch, SW-1 the corotron so selected the s f f h Xewgraphie Plate With the powder is connected to a high potential power supply. 40 image h ring thereto.

In order to assure proper alignment of the sheet of while the present invention as to its objects and advan Support i l i h th xerographic l t u f a tages, as described herein, has been carried out in specific sheet registration guide 86 is provided beneath the surface embodiments thereof, it is t sir d to be limited of the inclined plate 40. The registration guide 86 is F Q Y but it is intended to covar the? invention broadly attached to the bottom of the plate 40 by means of bracket Wlthlh the Spirit and Scope of the pp Claims- 88. pivotally connected to a second bracket 90. What is claimed The registration guide 86 is constructed of a flat metal Apparatus for trahsfel'lhlg Powdef images from a sheet bent at one end to extend up beyond the end of in- XeTOgTaPhiC Plate to a Sheet of pp matelial includclined plate 40 and above the surface thereof so that a h1g1 sheet of support material on the inclined plate will abut a frame adapted PP a Xefographic Plate in a the guide 86 and be properly aligned for feeding onto the 50 P i i to have P image thereon, tTaflSfelTed surface of the xerographic plate. The other end of the to asheet 0f PP material,

guide 86 i spring w d d b means f Compression spring an electrostatic transfer device spanning the xero- 92 forcing the guide 86 to pivot about the brackets 88 and aphie Plate and moveahle PP y the frame, 90 so that the end of the guide 86 is normally in interto traverse the Xefographic P ference relationship with a sheet of support material on 111691115 to feed a Sheet of pp material Onto the the inclined plate surface. A deflector 94 is mounted on Surface the Xerographic Plate as the tr s ti each of end of the shaft 44 and passes downward beside charging device traverses the Plate,

the plate 40 to deflect the guide 85 dgvmward against said sheet feeding means arranged for movement with the action of spring 92 thereby permitting passage f h said electrostatic transfer device and operative to sheet of support material 38. The shaft 44 containing fe d the sheet of support material at a rate substanthe two plnions 48 is journaled in the bushings 46 and tially equal to the rate of movement of the electro- 1s movable 1n a vertical direction in slots 96 in side plates Static Charging device across the plate Sulface a 32 and 36. The shaft 44 is held downward so that the When inoperative to arrest the Sheet in Close h drive rollers 42 are pressed against the surface of the inimity With Said Xeroglaphl'c P clined plate 40 by means of a leaf spring 98 seen in detail and means to p y an electrical Potential t0 the elec- 1n FIG. 4. trostatic charging device to electrostatically tack the I V rtic l movement of the shaft 44 and the drive rollers pp rt m erial to h pl surface and to transfer 42 1s accompllshed by depressing a large button 102 a powder image from the plate to the support matewhich extends through an opening in the top cover of, rial.

the transfer device. -An actuating member 104 is secured 2. An apparatus for transferring powder images from to the bottom of the button 102 and when depressed a xerographic plate to a sheet of support material downward against the action of compression spring 106, including:

mounted between the top cover of the transfer device and means to support a Xerographic plate containing a the support member 50, pulls a pair of chains 107 secured powder image thereon,

an electrostatic charging device positioned to span a xerog-raphic plate on the support means,

said electrostatic charging device being moveable over the length of the Xerogr phic plate to completely traverse the late surface,

a support material guide plate arranged for movement with said electrostatic charging device and positioned to guide a sheet of support material between the electrostatic charging device and the xerographic plate,

sheet feeding means arranged for movement with said electrostatic device and including at least one roller mounted for rotation in operative position relative to the guide plate to feed a sheet of support material from the guide plate onto the surface of the Xerographic plate,

means to substantially synchronize the sheet feeding rate with the movement of the electrostatic charging device across the surface of the xerographic plate,

and means to apply an electrical potential to the electrostatic charging device to electrostatically tack the support material to the xerographic plate surface and to transfer a powder image from the Xerographic plate to the support material.

3. An apparatus for transferring powder images from a xerographic plate to a conductive sheet of support material including:

means to support a Xerographic plate containing a powder image thereon,

an electrostatic charging device positioned to span a Xerographic plate on the support means,

said electrostatic charging device being movable over the length of the xerographic plate to completely traverse the plate surface,

means including at least one drive roller mounted for rotation and arranged for movement with said electrostatic charging device to feed a sheet of conductive support material onto the surface of the Xerographic plate, said drive rollers being positioned downstream in path of the electrostatic charging device whereby said conductive support material is placed onto said xerographic plate after the electrostatic charging device traverses the plate,

means to substantially synchronize the movement of the sheet feeding means with the movement of the electrostatic charging device,

means to apply an electrical potential to the electrostatic charging device to thereby electrostatically charge the surface of the xerographic plate immediately prior to the sheet of support material being placed thereon,

and means to shield the plate surface from ambient light during and after charging.

4. An apparatus for transferring powder images from a Xerographic plate to a sheet of support material including:

means to support a Xerographic plate containing a powder image thereon,

a transfer device mounted above the spanning the surface of a Xerographic plate and being movable over the length thereof,

said transfer device containing a first electrostatic charging device, a second electrostatic charging device, a support material guide plate and a sheet feediug means,

the support material guide plate being positioned relative to the first and second electrostatic charging devices so that a sheet of support material thereon will be fed by the sheet feeding means between the first electrostatic charging device and the second electrostatic charging device onto the surface of a Xerographic plate,

the first electrostatic charging device being positioned in the transfer device to place an electrostatic charge on the surface of a sheet of support material on the Xerographic plate surface,

said second electrostatic charging device being positioned in the transfer device to place an electrostatic charge on the xerographic plate surface before a sheet of support material is placed thereon,

and means to apply an electrical potential to either said first charging device or said second charging device to tack a sheet of support material onto the Xerographic plate surface and to transfer a powder image from the plate surface to the sheet of support material.

5. Apparatus for transferring a powder image from a Xerographic plate to a sheet of support material comprising a frame to support a xerographic plate having a powder image thereon in a substantially horizontal plane, contiguous walls forming an open bottom housing slidably supported on said frame for bidirectional horizontal movement across said xerographic plate, a one of said walls being arranged at an acute angle with the horizontal plane and adapted to guide a sheet of support material onto said Xerographic plate, a corotron supported by side walls of said housing to extend transverse to the path of said housing and parallel to the xerographic plate,

rotary feed means including at least one roller mounted for rotation on a shaft journaled in said housing and movable from a first position with said rollers in pressure contact with said guide wall to advance the support web onto said xerographic plate to a second position with said rollers spaced from said guide wall,

drive means connected to said shaft to rotate said xerographic plate simultaneously with the movement of said housing at a rate equal thereto, and

means to apply an electrical potential to the electrostatic charging device to electrostatically tack the support material to the plate surface and to transfer a powder image from the plate to the support material.

6. Apparatus according to claim 5 wherein said support sheet is a conductive material and said corotron is positioned upstream in the roller path whereby the electrostatic charge may be applied to the surface of the xerographic plate ahead of said support material.

7. Apparatus according to claim 5 including control means to vary the spacing between said corotron and said xerographic plate.

References Cited by the Examiner UNITED STATES PATENTS 2,684,901 7/1954 Sabel et al. 118-637 X 2,684,902 7/1954 Mayo et a1. 1l8637 3,150,004 9/1964 Murray et al. 118637 CHARLES A. WILLMUTH, Primary Examiner. PETER FELDMAN, Assistant Examiner. 

1. APPARATUS FOR TRANSFERRING POWDER IMAGES FROM A XEROGRAPHIC PLATE TO A SHEET OF SUPPORT MATERIAL INCLUDING: A FRAME ADAPTED TO SUPPORT A XEROGRAPHIC PLATE IN A POSITION TO HAVE A POWDER IMAGE THEREON, TRANSFERRED TO A SHEET OF SUPPORT MATERIAL, AN ELECTROSTATIC TRANSFER DEVICE SPANNING THE XEROGRAPHIC PLATE AND MOVEABLE SUPPORTED, BY THE FRAME, TO TRAVERSE THE XEROGRAPHIC PLATE, MEANS TO FEED A SHEET OF SUPPORT MATERIAL ONTO THE SURFACE OF THE XEROGRAPHIC PLATE AS THE ELECTROSTATIC CHARGING DEVICE TRAVERSES THE PLATE, SAID SHEET FEEDING MEANS ARRANGED FOR MOVEMENT WITH SAID ELECTROSTATIC TRANSFER DEVICE AND OPERATIVE TO FEED THE SHEET OF SUPPORT MATERIAL AT A RATE SUBSTANTIALLY EQUAL TO THE RATE OF MOVEMENT OF THE ELECTROSTATIC CHARGING DEVICE ACROSS THE PLATE SURFACE, AND WHEN INOPERATIVE TO ARREST THE SHEET IN CLOSE PROXIMITY WITH SAID XEROGRAPHIC PLATE, 